The field of the invention relates generally to electric motors, and more specifically, to systems and methods that facilitate replacing an induction motor with an electrically controlled variable speed motor in aquatic applications.
One of many uses of an electric motor is to operate a pump, and in turn, move a fluid. Examples of aquatic applications for pumps include pools, spas, and hot tubs. Such applications include a basin or tub structure that holds a supply of water and a circulation pump system. For example, the circulation pump system may include a pump and a pump motor. The pump, in combination with the pump motor, facilitates water filtering and heating by removing water from the tub structure, through a filter and/or heater, and returning the water into the tub structure.
A common motor used in such pump systems is an alternating current (AC) induction motor, for example, a single-speed AC induction motor or a two-speed AC induction motor. The two-speed AC induction motor is configured to operate at a high speed and at a low speed. At the low speed, a rate of water flowing through the pump is decreased when compared to the motor operating at the high speed. The pump motor operating at low speed consumes less electrical power, although, cost savings from lower energy consumption may be offset because the pump system has to operate for a longer period of time at the low speed to circulate the same amount of water as the pump system at high speed.
Other types of motors may be included in a pump system, for example, electronically commutated motors (ECM). Examples of ECMs are brushless direct current (BLDC) motors, permanent magnet alternating current (PMAC) motors, and variable reluctance motors. Typically, these motors provide higher electrical efficiency than an AC induction motor. ECMs also facilitate variable speed operation of the pump system. Therefore, replacing an AC induction motor in a pool, spa, or hot tub with an ECM typically will reduce the operating costs associated with heating and/or filtering the pool, spa, or hot tub. However, ECMs and AC induction motors are not interchangeable, due at least in part to differences between how ECMs and AC induction motors are powered and controlled. The speed at which a two-speed AC induction motor operates depends upon which of two inputs receives an electrical power. A voltage, for example, a 115 VAC or 230 VAC voltage, is provided to either a high speed power line or a low speed power line. The two-speed AC induction motor operates at a high speed when operating power is provided to the high speed power line, and to high speed coils, of the AC induction motor. The two-speed AC induction motor operates at a low speed when operating power is provided to the low speed power line, and to low speed coils, of the AC induction motor. In contrast, an ECM typically receives an operating power from a power source at a motor drive unit, and varies a speed of operation of the motor based on a low-voltage control signal.